Since I started commuting regularly, and seriously--as in riding on the street, wearing a helmet, following the rules, looking like I know what I' m doing--I have been "instructed" to use the sidewalk twice by passing cars, that is, someone in a passing car has shouted "sidewalk" at me. Other than that, nothing.

Thirty years ago, someone threw some water at me, and some old guy turned into a parking lot and clipped my rear wheel.

Good point above about close calls while driving. Twice I just about have gotten my kids killed by a boneheaded maneuver on my part in a car. Where I live in Minneapolis, my route TO work is in the morning when traffic is lighter, and my route FROM work is longer along the side streets, so I personally feel safer on a bike than in a car.

I used to ride out in heavy traffic in rush hour on a four-lane street until I found my quieter, longer, back way home. Even then, I never had any incident that I would consider any sort of problem.